This invention relates to a tubular turbine-generator of the bulb type adapted to be used in a small head, and more particularly, to a device for supplying lubrication oil into a rotating shaft bearing portion of such a bulb type turbine-generator.
Generally, a tubular turbine-generator comprises the combination of a Kaplan type turbine having a horizontal or slant shaft and an electric power generator, and two types of tubular turbine generators are known such as a pit type and a bulb type. In the former type, the electric power generator is accommodated in a pit made of, for example, concrete material, and flow paths are formed at both sides thereof. In the latter type, an inner casing is centrally supported in an outer casing by stay vanes and the flow path is defined between the inner and outer casings, the inner casing being of bulb shape to fluid-tightly house the electric power generator therein. The present invention is directed to the latter type of turbine-generator.
An apparatus of relatively large size permitting rotary movement, such as a turbine-generator, requires large amounts of cooled lubrication oil, since its bearing portion generates large amounts of heat due to thermal friction. In the case of the bearing for supporting an upstanding rotary shaft, a self-lubrication-cooling system is adopted, wherein lubricating oil is accumulated in the bearing to which a cooling pipe is connected. Therefore, relatively easy cooling lubrication can be performed. On the other hand, in the case of the bearings for supporting a horizontal rotary shaft, for example those in the main shaft of the tubular turbine-generator, the self-lubrication cooling system is not available due to the mechanical disposition, and therefore, a lubrication oil recirculation system is generally adopted therein which forcibly supplies lubrication oil into the bearing portion. This is shown in FIG. 1.
In FIG. 1, a rotary shaft 1 is supported by a bearing 2 having one end connected to an upper oil tank 3 through a conduit 7 and the other end connected to a lower oil tank 4 to collect the used oil. The lower oil tank 4 is connected to a cooling chamber 6 through a return conduit 8 to supply heated oil in the tank 6 thereinto by a pump 5 disposed in the conduit 8. The cooling chamber 6 is connected to the upper tank 3 to supply cooled oil thereinto. The tank 3 and cooling chamber 6 are disposed outside of the bulb type turbine.
The lubricating oil accumulated in the upper tank 3 is forcibly recirculated in the oil circuit in the direction shown by an arrow A to coolingly lubricate the bearing portion, and the upper oil tank 3 continuously supplies oil into the bearing portion until the termination of the rotary operation even if the oil pump 6 becomes inoperative.
Accordingly with the conventional bulb-type tubular turbine generator, the lubricating oil recirculation system as shown in FIG. 1 is employed, and therefore, the upper tank 3 and the cooling chamber 6 are not disposed in the bulb shaped inner casing (hereinafter simply referred to as "bulb") due to the lack of space. The upper tank and the cooling chamber are installed in the building of the power plant and are connected by long oil conduits to the bearing portion of the turbine-generator accomodated in the bulb. Therefore, such construction requires large space and the power plant building should provide enough room to install the tank and chamber. This is costly and results in a mechanically complicated structure.
Further, conventional small size bulb type tubular turbine-generators of the type having relatively small capacity used in low head, have disadvantages in terms of installation. That is, the bulb-shaped inner casing, the outer casing and the stay vanes are integrally assembled at a factory, but are detachably subdividable into a plurality of pieces along the transverse direction thereof for easy transportation to the installation site. The transversely subdivided pieces are transported to the construction field and are connected with each other at the site.
However, such assembling work is extremely troublesome, requires long periods of time, and the turbine and the electrical power generator must be precisely incorporated into the casing. This requires skillful workers sometimes not available. Further, overhaul of such a device is extremely troublesome.